Data archiving refers to techniques for storing large amounts of data for potentially long periods of time and for providing efficient retrieval of relevant portions of the data when it is necessary to do so. Data archiving is employed for a variety of purposes, one of which is to comply with government-driven or policy-driven data retention requirements. Another is to reduce the size and increase the performance of large online database systems by purging some of the database contents into one or more archives.
Inevitably, the size of an archive site for database applications can be enormous. An archive for a terabyte-sized database application might be measured, for example, in petabytes.